This invention relates to the stacking of printed sheets of paper at the outfeed of a printing press, and more particularly to the inclusion in the stack of a plurality of backing boards separating the stack into a plurality of groups each containing a predetermined number of printed sheets.
Pads of printed paper sheets are made by assembling a predetermined number of printed sheets together with a backing sheet of stiff paperboard or the like, and gluing the assembly together at one edge. This is usually accomplished by inserting a plurality of backing boards at number intervals in the stack of printed sheets formed at the outfeed of a printing press.
The insertion of backing boards heretofore has been done manually, either as the stack is being formed, or after a formed stack is removed from the vicinity of the printing press. In the latter case, the counting of sheets into groups has been done either entirely manually, or by the use of a comb-like device that is inserted edgewise into the stack to form groups of approximate numbers. Backing boards then are inserted at the comb teeth separations. Alternatively, tabs are inserted into the stack at intervals as the sheets are counted by the printing press and then each tab is replaced manually with a backing board. In any case, the manual operation is time consuming and costly in terms of labor and production.
U.S. Pat. No. 4,624,452 discloses a board inserter that functions to insert a board onto a pre-counted stack of printed sheets while fingers intercept the path of the next following printed sheet momentarily to provide a space between sheets into which the board may be inserted. The mechanism by which the fingers are operated and controlled is complex, costly to produce and maintain and susceptible of faulty operation.